Conventionally, for a base station apparatus in a macro cell or the like, experts conduct field investigation in advance, and perform station placement design and parameter optimization (e.g. see Patent Literature 1). Therefore, the base station apparatus in a macro cell or the like is normally assigned a cell ID that minimizes inter-cell interference between neighboring cells.
Furthermore, the development of small base station apparatuses called “femto cells” is in progress to eliminate dead zones of mobile phones in recent years. Unlike the macro cell, the femto cell is installed by a general user as appropriate. Therefore, the femto cell is installed by the user in an arbitrary place without considering any interference with peripheral cells.
FIG. 1 is a diagram illustrating cells adjacent to each other. In FIG. 1, when, for example, a cell ID of macro cell #1 is “0xAC80” and a cell ID of macro cell #2 is “0xB92F,” macro cell #1 and macro cell #2 adjacent to each other do not interfere with each other. On the other hand, as shown in FIG. 1, when a general user installs femto cell #3 adjacent to both macro cell #1 and macro cell #2, if a cell ID of femto cell #3 is “0xAC80,” the cell ID of macro cell #1 is identical to the cell ID of femto cell #3, and therefore macro cell #1 and femto cell #3 interfere with each other. When such inter-cell interference occurs, it is necessary to reset parameters of the femto cell.
Citation List
Patent Literature
PTL 1
Japanese Patent Application Laid-Open No. 2008-172380